The purpose of this study is to evaluate the effectiveness of a cochlear implant and a (vibro)tactile aid in promoting the development of oral communication skills in totally deaf children who receive no benefit from conventional hearing aids. There will be two experimental groups with 20 subjects in each group: a group comprised of children who use a single-channel cochlear implant and a group comprised of children who use a wearable, tactile aid. The children in the two groups will be matched, as closely as possible, with respect to age of onset of deafness, chronological age, and length of acoustic deprivation between the onset of deafness and receipt of their sensory aid. The children's speech production and perception skills will be examined, on a longitudinal basis, to: (1) determine the features of speech which are perceived via a cochlear implant or tactile aid; (2) to evaluate the effectiveness of a cochlear implant or tactile aid as a speech production aid by studying the development of phonetic contrasts and prosodic features acquired by these children; and (3) to examine the relationship between production and perception skills by determining which features of speech perceived by each child are reflected in his/her speech. Perceptual and acoustic analysis techniques will be used to provide a detailed, quantitative mapping of each child's speech development. Innovative techniques will be used to assess the production and perception skills of those children who have very reduced cognitive and communicative skills. Examination of their speech skills will employ acoustically-based analyses schemes which are similar to those used to study the speech of developing infants. Perception skills will be evaluated using a video game format. Operational definitions for determining device effectiveness are specified by two methods. First, the performance of the subjects in the two experimental groups will be compared to that of their profoundly hearing-impaired peers who do receive some benefit from amplification. The performance of the hearing-aid users will represent the optimal performance level to be achieved by the subjects in the experimental groups. Secondly, each subject will serve as his/her own control to determine if significant changes occur in a specified set of skills that, at the very least, should be acquired by these children. The second analysis will provide an estimate of the minimal performance-levels that are needed to demonstrate the efficacy of each device in promoting oral communication skills in the subjects under study.